[Intel-gfx] [PATCH 09/13] drm/i915: Extend I915_CONTEXT_PARAM_SSEU to support local ctx->engine[]

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-03-11 07:16:48)
> 
> On 08/03/2019 17:11, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-03-08 16:31:51)
> >> Looks okay. But one more thing is needed:
> >>
> >> https://cgit.freedesktop.org/~tursulin/drm-intel/commit/?h=media&id=38266bfe99469de9e13774a13fa641c377988c67
> > 
> > drm/i915: Allow SSEU configuration to be set on virtual engine
> > 
> >       /* Only render engine supports RPCS configuration. */
> > -     if (engine->class != RENDER_CLASS)
> > +     if (engine->class != RENDER_CLASS &&
> > +         !(engine->flags & I915_ENGINE_IS_VIRTUAL &&
> > +           ctx->engines[1]->class == RENDER_CLASS))
> >               return -ENODEV;
> > 
> > A virtual engine composed of RCS engines would have
> > engine->class == RENDER_CLASS.
> > 
> > So it's just the engine->id BUG_ON that needs lifting?
> 
> If so then yes. Must be a recent change since I was sure the class was 
> set to other before.

uabi_class = OTHER
internal_class = ACTUAL and used to restrict physical engines to only
belong to the same class (no load balancing across classes today).

I _think_ we had that from the start, at least I remember wanting to do
mixed class load-balancing but realising that I had to filter on class
to avoid engine->emit_* mixups.
-Chris